The present invention relates to a liquid crystal display device, and more particularly to the liquid crystal display device which is arranged to improve shortage of an auxiliary capacitance caused by keeping the display high-definitive.
A request is rising for making small-sized liquid crystal display devices to be used for mobile phones or digital cameras more and more high-definitive. Among the liquid crystal display devices, so-called IPS (In-Plane Switching) type liquid crystal display device arranged to apply a horizontal electric field is advantageous in wide viewing angle. Among the IPS type liquid crystal displays, the liquid crystal display devices arranged to have a pixel structure composed of comb-like pixel electrodes and planar common electrodes is advantageous in that the overlapped portion between the transparent pixel electrode and the transparent common electrode is used as a capacitance auxiliary to the liquid crystal capacitance. However, as the display is made more and more high-definitive, disadvantageously, the ratio of the area of the pixel electrodes is made smaller, and accordingly the auxiliary capacitance becomes short.
As mentioned above, the IPS type liquid crystal display device (referred to as the IPS type LCD device) is arranged so that the comb-like pixel electrodes are located as opposed to the planar common electrodes with an insulating film laid therebetween. One of the advantages of the IPS type LCD device is generation of a transparent auxiliary capacitance between the pixel electrode and the common line. The method of realizing a brighter display as keeping the high viewing angle specific to the IPS type has been proposed in JP-A-2003-207795, JP-A-2005-338256 and JP-A-2006-126602.